Improve pth_cvsimple test in two ways:

1. Make the output deterministic;  different thread interleaving from expected
was causing failures for me.

2. Make it actually use the condition variable -- the condvar stupidly wasn't
actually being used in the expected case, because the other threads finished
all their work before pthread_cond_wait() even got called, and this prevented
the condition guarding pthread_cond_wait() from succeeding.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@2952

corecheck/tests/pth_cvsimple.c

@@ -9,7 +9,7 @@
  *
  * cvsimple.c
  *
- * Demonstrates pthread cancellation.
+ * Demonstrates pthread condvars.
  *
  */
 
@@ -20,23 +20,22 @@
 #define TCOUNT 10
 #define COUNT_THRES 12
 
+int     condvar_was_hit = 0;
 int     count = 0;
 int     thread_ids[3] = {0,1,2};
 pthread_mutex_t count_lock=PTHREAD_MUTEX_INITIALIZER; 
 pthread_cond_t count_hit_threshold=PTHREAD_COND_INITIALIZER; 
 
-void *inc_count(void *idp)
+void *inc_count(void *null)
 {
   int i=0;
-  int *my_id = idp;
 
   for (i=0; i<TCOUNT; i++) {
     pthread_mutex_lock(&count_lock);
     count++;
-    printf("inc_counter(): thread %d, count = %d, unlocking mutex\n", 
-	   *my_id, count);
+    printf("inc_counter(): count = %d, unlocking mutex\n", count);
     if (count == COUNT_THRES) {
-      printf("inc_count(): Thread %d, count %d\n", *my_id, count);
+      printf("hit threshold!\n");
       pthread_cond_signal(&count_hit_threshold);
     }
     pthread_mutex_unlock(&count_lock);
@@ -45,17 +44,13 @@ void *inc_count(void *idp)
   return(NULL);
 }
 
-void *watch_count(void *idp)
+void *watch_count(void *null)
 {
-  int *my_id = idp;
-
-  printf("watch_count(): thread %d\n", *my_id);
-  fflush(stdout);
   pthread_mutex_lock(&count_lock);
 
   while (count < COUNT_THRES) {
     pthread_cond_wait(&count_hit_threshold, &count_lock);
-    printf("watch_count(): thread %d, count %d\n", *my_id, count);
+    condvar_was_hit = 1;
   }
 
   pthread_mutex_unlock(&count_lock);
@@ -69,14 +64,26 @@ main(void)
   int       i;
   pthread_t threads[3];
 
-  pthread_create(&threads[0], NULL, inc_count, (void *)&thread_ids[0]);
-  pthread_create(&threads[1], NULL, inc_count, (void *)&thread_ids[1]);
-  pthread_create(&threads[2], NULL, watch_count, (void *)&thread_ids[2]);
+  pthread_create(&threads[0], NULL, watch_count, NULL);
+  pthread_create(&threads[1], NULL, inc_count,   NULL);
+  pthread_create(&threads[2], NULL, inc_count,   NULL);
 
   for (i = 0; i < NUM_THREADS; i++) {
     pthread_join(threads[i], NULL);
   }
 
+  // Nb: it's not certain that we'll hit here.  It's possible that the two
+  // inc_count threads could fully run before watch_count begins, and so
+  // pthread_cond_wait() is never called.  Or, we could get a spurious
+  // wake-up in watch_count().  Nonetheless, it's very likely that things
+  // will work out as expected, since we're starting watch_count() first.
+  if (condvar_was_hit == 1)
+    printf("condvar was hit!\n");
+  else if (condvar_was_hit > 1)
+    printf("condvar was multi-hit...\n");
+  else
+    printf("condvar was missed...\n");
+  
   return 0;
 }
 

corecheck/tests/pth_cvsimple.stdout.exp

@@ -1,22 +1,22 @@
-inc_counter(): thread 0, count = 1, unlocking mutex
-inc_counter(): thread 0, count = 2, unlocking mutex
-inc_counter(): thread 0, count = 3, unlocking mutex
-inc_counter(): thread 0, count = 4, unlocking mutex
-inc_counter(): thread 0, count = 5, unlocking mutex
-inc_counter(): thread 0, count = 6, unlocking mutex
-inc_counter(): thread 0, count = 7, unlocking mutex
-inc_counter(): thread 0, count = 8, unlocking mutex
-inc_counter(): thread 0, count = 9, unlocking mutex
-inc_counter(): thread 0, count = 10, unlocking mutex
-inc_counter(): thread 1, count = 11, unlocking mutex
-inc_counter(): thread 1, count = 12, unlocking mutex
-inc_count(): Thread 1, count 12
-inc_counter(): thread 1, count = 13, unlocking mutex
-inc_counter(): thread 1, count = 14, unlocking mutex
-inc_counter(): thread 1, count = 15, unlocking mutex
-inc_counter(): thread 1, count = 16, unlocking mutex
-inc_counter(): thread 1, count = 17, unlocking mutex
-inc_counter(): thread 1, count = 18, unlocking mutex
-inc_counter(): thread 1, count = 19, unlocking mutex
-inc_counter(): thread 1, count = 20, unlocking mutex
-watch_count(): thread 2
+inc_counter(): count = 1, unlocking mutex
+inc_counter(): count = 2, unlocking mutex
+inc_counter(): count = 3, unlocking mutex
+inc_counter(): count = 4, unlocking mutex
+inc_counter(): count = 5, unlocking mutex
+inc_counter(): count = 6, unlocking mutex
+inc_counter(): count = 7, unlocking mutex
+inc_counter(): count = 8, unlocking mutex
+inc_counter(): count = 9, unlocking mutex
+inc_counter(): count = 10, unlocking mutex
+inc_counter(): count = 11, unlocking mutex
+inc_counter(): count = 12, unlocking mutex
+hit threshold!
+inc_counter(): count = 13, unlocking mutex
+inc_counter(): count = 14, unlocking mutex
+inc_counter(): count = 15, unlocking mutex
+inc_counter(): count = 16, unlocking mutex
+inc_counter(): count = 17, unlocking mutex
+inc_counter(): count = 18, unlocking mutex
+inc_counter(): count = 19, unlocking mutex
+inc_counter(): count = 20, unlocking mutex
+condvar was hit!